It is very desirable to provide a material from aqueous solution that will condition the hair and still be compatible with anionic surfactants. This allows for the preparation of clear two in one shampoo systems, clear 2 in one shower gels, and clear two in one bath products. By two in one products in meant, a product that contains both anionic surfactant, most commonly sulfates and ether sulfates and a cationic conditioning agent. The anionic surfactant is the detergent, which cleans the hair or skin, and the cationic product is for conditioning providing softness, slip and feels to the skin. The problem with such product has always been the incompatibility of the anionic and cationic surfactants with each other. When many of these products are present in the same solution an insoluble salt forms making a cosmetically unacceptable white gunk that does not stay in solution.
As will become clear, by making a very large molecule the present invention results in a we call a soft quaternary compound. By soft quaternary compound is meant one that not withstanding its cationic charge is of a structure so that when placed in water along with the anionic surfactant, a clear stable solution is obtained. Surprisingly, because of the high molecular weight of the quaternary compound, the deposition on the hair and skin is increased. While not wanting to be held to only one mechanism, we believe there rather than a precipitate observed with so-called hard quats, compounds of the present invention form a self-assembling complex between the anionic and cationic surfactant. This complex, while water-soluble is large enough to disrupt hydrogen bonding between water molecules, and as such energetically, the complex will be deposited on the skin or hair leaving the remaining solution at the lowers free energy level.
The self-assembling aspect of the present invention, which we believe is the result of orientation of the salt of the cationic compounds of the present invention and the anionic surfactants present in solution, can be demonstrated by the fact that upon initial mixing of the components, a hazy or cloudy dispersion occurs. With suitable mixing, this hazy dispersion becomes a solution and the viscosity increases.
The compounds of the present invention can be formulated into body washes and other skin products and hair care products to provide a “delivery system” for conditioning the hair or skin. The high molecular weight of the quat and the fact that the point charges are far apart in the molecule results in through and efficient deposition on the hair or skin. This provides uniformity of conditioning agent over the entire hair of skin surface. This is particularly important for applications on hair for people with long hair. In general the long hair is more damaged, dry and in need of conditioning at the tip area, than near the root. The hair closest to the scalp is newer, less damaged, and less in need of conditioning. This dichotomy of hair condition is more effectively treated by the complexes formed by the current invention than by other quats. In addition, the di-nature of the compounds provides for outstanding substantivity of the molecule allow for very mild natural like materials that can be used in products where low irritation is important.
U.S. Pat. No. 6,331,293 issued Dec. 18, 2001 to Smith et al describes phosphobetaines that are derived from dimer acid. Unlike the compounds of the present invention, these materials are amphoteric surfactants and are barriers when applied to the skin. It is stated that the compounds are “extremely substantitive to human skin and are well tolerated by human tissue making them suitable for use preparation of barrier products for personal care applications”. Unlike these materials, the compounds of the present invention are not amphoterics, but are quats, are not barriers but are conditioning agents that do not build up on the hair or skin.